Calcium ion fluorescence detection using liposomes containing Alexa-labeled calmodulin.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Materials Science

Background:

• Accurate calcium ion (Ca2+) determination is crucial in biological and environmental samples.
• Existing methods for Ca2+ detection can be limited by sensitivity or stability.
• Fluorescent probes offer potential for sensitive and real-time monitoring of Ca2+.

Purpose of the Study:

• To develop and characterize novel calcium ion-sensitive fluorescent liposomes.
• To evaluate the performance of these liposomes for Ca2+ determination in aqueous samples.
• To investigate the impact of liposomal encapsulation on calmodulin's Ca2+ binding properties.

Main Methods:

• Preparation of unilamellar liposomes encapsulating Alexa-488 labeled calmodulin (Alexa-CaM).
• Characterization of liposome structure and stability.
• Spectroscopic analysis of fluorescence intensity changes upon Ca2+ binding.
• Comparison of Ca2+ binding kinetics and response of liposome-embedded Alexa-CaM versus free Alexa-CaM.

Main Results:

• Liposomal encapsulation significantly extended the Ca2+ binding lifetime of calmodulin by approximately fourfold.
• The Ca2+ response of liposome-embedded Alexa-CaM was enhanced threefold compared to free Alexa-CaM.
• Improved Ca2+ detection properties are attributed to interactions between calmodulin and liposomal phospholipids.
• The study discusses the analytical properties of the developed fluorescent liposomes.

Conclusions:

• Fluorescent liposomes incorporating calmodulin offer superior Ca2+ detection capabilities compared to free probes.
• Liposomal formulation enhances the stability and sensitivity of calmodulin-based Ca2+ sensing.
• These liposomes represent a promising tool for sensitive and reliable determination of calcium ions in aqueous environments.